shear bond strength of a resin cement to different alloys subjected to various surface treatments

objectives: micromechanical retention of resin cements to alloys is an important factor affecting the longevity of metal base restorations. this study aimed to compare the bond strength and etching pattern of a newly introduced experimental etchant gel namely nano met etch with those of conventional surface treatment techniques for nickel-chrome (ni-cr) and high noble alloys.  materials and methods: a total of 120 discs (8×10×15 mm) were cast with ni-cr (n=20), high noble begostar (n=50) and gold coin alloys (n=50). their surfaces were ground with abrasive papers. ni-cr specimens received sandblasting and etching. high noble alloy specimens (begostar and gold coin) received sandblasting, sandblasting-alloy primer, etching, etch-alloy primer and alloy primer alone. cylindrical specimens of panavia were bonded to surfaces using tygon tubes. specimens were subjected to micro-shear bond strength testing after storing at 37°c for 24 hours. results: in gold coin group, the highest bond strength was achieved after sandblasting (25.82±1.37mpa, p<0.001) and etching+alloy primer (26.60 ± 5.47 mpa, p<0.01). the lowest bond strength belonged to sandblasting+alloy primer (17.79±2.96mpa, p<0.01). in begostar group, the highest bond strength was obtained in the sandblasted group (38.40±3.29mpa, p<0.001) while the lowest bond strength was detected in the sandblast+ alloy primer group (15.38±2.92mpa, p<0.001). for the ni-cr alloy, bond strength in the etched group (20.79±2.01mpa) was higher than that in the sandblasted group (18.25±1.82mpa) (p<0.01). conclusions: for the ni-cr alloy, etching was more efficient than sandblasting but for the high noble alloys, higher au content increased the efficacy of etching.